The ultimate high-pressure job: surviving on the seabed

A rich menagerie of animal life has been discovered on the deepest seabed in the world where the pressure is a crushing 16,000lbs per square inch.

A rich menagerie of animal life has been discovered on the deepest seabed in the world where the pressure is a crushing 16,000lbs per square inch.

A team of Japanese and British marine biologists found delicate, soft-walled creatures dominate the microbial life-forms that inhabit the sediment at the bottom of a deepwater trench in the Pacific. The trench, called Challenger Deep, lies 400 miles off the Marianas Islands in the south Pacific. At its deepest, the trench would submerge Mount Everest in a mile-deep layer of water.

Yuko Todo, of Shizuoka University in Japan, and Andrew Gooday, of the Southampton Oceanography Centre, recovered the deep-sea microbes using a robot submersible.

"Extreme depths make it very difficult to sample the bottom of deep-ocean trenches," the scientists say in the journal Science . "As a result, almost nothing is known about small, sediment-dwelling organisms - meiofauna - in these environments."

The submersible collected sediment samples that yielded 432 types of microbial plankton.

The Challenger Deep has formed over six million to nine million years by tectonic plates grinding over each other. The scientists believe the plankton life has evolved from other deep-ocean microbes that gradually became acclimatised to deeper and deeper seabeds.

"Its distinctive foraminiferal fauna probably represent the remnants of an abyssal assemblage that was able to adapt to the steady increase in hydrostatic pressure over this period," the scientists say.